After Effects crashing on puppet pin tool... Error: Crash occurred while invoking plug in 'puppet'

I've tried several times to place a pin on a shape layer, but it crashes every time. My shape layer has 2 groups, each group has multiple groups within it. Each time, I select the shape layer, then select the puppet pin tool, then when I click to place the first pin, the error dialog comes up and AE crashes with this message: "After Effects error: crash occurred while invoking plug-in "Puppet". I've used the puppet pin tool successfully several times before on this computer, this is the first time it has failed.

Specs:

After Effects CC v15.1.2 (just updated today) 

Mac OS High Sierra v10.13.6

Macbook Pro 2014

16 GB RAM (13 GB allocated to AE)

2.5 GHz Intel Core i7, 4 cores

NVIDIA GeForce GT 750M 2048 MB Intel Iris Pro 1536 MB

Disk cache is on a separate external hard drive, 500GB max disk cache size

The shape layer has a few nested groups, the hierarchy goes like this: Group 1>Group 1, 2>[8-10 groups each]

I imported the shape layer from AI using the Overlord plug-in; in AI, the shapes are grouped, and I set the Overlord settings to put all the shapes within one shape layer.

I've looked all over and can't find an answer... help??!